Hypodermic syringes having retractable needles are well-known in the art. These syringes are commonly used in healthcare industry to inject therapeutics below the skin of patients. Despite their utility, the hypodermic syringes pose significant safety risks to medical professionals, patients, children playing in a park, street walkers and anyone who could accidentally be pricked by exposed needle of the hypodermic syringe. After disposal, needle stick injuries resulting from contact with discarded needles are an increasing problem. The needle-stick injury is a percutaneous wound typically set by a needle-point before and after use. These events of occupational health hazards are of great concern because of the risk of transmitting blood-borne diseases through passage of hepatitis B virus (HBV), hepatitis C virus (HCV), Human Immunodeficiency Virus (HIV) and the like. Disposal of bio-medical waste also poses a large public health concern. As a result of the foregoing concerns, the safe fluid injecting systems are gaining more and more attention to avoid dangerous needle prick injuries.
Generally, an injectable drug (the fluid) is stored, packed and supplied conveniently by pharmaceutical industries in vials, ampoules and the like containers, which need hypodermic syringes to inject it into the body of human beings or animals. In conventional syringes, an operator first transfers a required volume of the drug into an empty hypodermic syringe by aspiration through the needle before injecting into the patient's body. In case of retractable syringes, a retraction mechanism operable on spring or a similar biasing means is activated to retract the needle into the barrel. After completion of an injection process, the empty vials, ampoules or container, the used hypodermic syringe along with their packaging material etc., which is generally made of non-biodegradable plastic, is finally disposed-off as bio-medical waste, adversely poses a considerable economic as well as environmental burden.
It is also important to note that the injectable drug packed by pharmaceutical industries is never filled into such containers up to the brim but approximately 20-40% volume of air always remains available in direct contact with packed drug during the entire course of storage. The oxygen, nitrogen and other active molecules present in such entrapped air also keep on interacting continuously with the molecules of drug contents, consequently a negative impact on the drug contents leading to ultimate decrease in the efficacy of drug may not be completely ruled out. On the other hand, before aspirating drug content into an empty syringe, the user first injects a current of air through hypodermic needle of empty syringe into such container in order to increase the pressure of air on the drug content, so that it may easily be aspirated into empty syringe by application of negative pressure. The air current forcibly injected into the drug may not be ruled out to contain harmful bio-active molecules or other pollutants except the normal ingredients of air like nitrogen, oxygen, carbon-di-oxide etc. The forceful current of such contaminated air pressed into injectable drug contents increases the probability of chemical interaction between such air and the drug contents to maximum extent due to dissolution of a considerable amount of air contents into drug contents at such high pressure. Under such circumstances, the adverse effect on the potency and efficacy of drug may also not be ruled out. Besides, such current of air passed into the drug contents at such higher pressure is also bound to generate millions of bubbles/micro-bubbles of entrapped polluted air, which are aspirated into the empty syringe. The user may, however, take care of visible bubbles of air but he may never avoid the millions of micro-bubbles entering directly into the blood stream of patient and posing adverse/undesirable impact on patient. We, however, could not find any discussions/literature on these issues, but these issues may not be neglected and need be effectively addressed. We strongly advocate that the injectable drug contents should never come in contact of air contents at any time and the drug need be injected directly into the patient without its being transferred into any other container like empty syringe, so that the potency of drug contents may be maintained and guarded zealously, right from the stage of manufacturing up to its administration into the patient's body.
There have been a number of solutions provided for efficient hypodermic syringes with retractable needles and few of them have been discussed below:
US20060264840A1 describes a retractable needle safety syringe. The syringe comprises a syringe body, a syringe cavity, a plunger, a variable vacuum compartment, a shaft brake, and a ram member. The plunger assembly includes a plunger shaft and a piston slidably engaged within the syringe body. The variable vacuum compartment being operative to provide a vacuum force on the plunger shaft directed from a bottom syringe body end toward a top syringe body end. The shaft brakebeing operative to frictionally engage the plunger shaft to provide first and second frictional forces in opposition to the vacuum force, the first frictional force being exerted prior to the piston reaching the bottom syringe body end, the second frictional force being exerted in response to the engagement of the ram member with the shaft brake. Further, the second frictional force is less than the first frictional force.
US6712787B1 describes a retractable safety syringe. The retractable safety syringe retracts a needle cannula into a plunger module and thus prevents reuse or an accidental needle prick by destroying a plunger barrier and a cannula barrier within the syringe. Further, the needle cannula is released into the plunger module by shearing the cannula barrier and the plunger barrier with an internal annular shear and cutter head.
U.S. Pat. No. 9,097,435B2 describes a retractable needle fluid transfer device. The device includes a manually operable actuator. Upon depressing the actuator, a spring displaces a needle rearwardly to enclose a contaminated needle. The device includes forward and rearward stops for impeding displacement of the needle after the needle is retracted. A safety sampling access port adapter for obtaining fluid samples from a fluid line is also disclosed. The sampling adapter includes a collapsible socket configured to cooperate with a fluid container such as a vacuum tube. Further, a needle assembly is provided to pierce aseal on the fluid container. After use, the socket is collapsed to prevent contact with the contaminated needle.
The aforesaid documents and other similar solutions may strive to provide efficient hypodermic syringes with retractable needles; however, they still have a number of limitations and shortcomings such as, but not limited to, relatively low reliability and relatively high complexity as well as relatively high manufacturing cost. Another disadvantage of these hypodermic syringes is the inability to evacuate the entire contents of the injectable drug from cavity. Further, these syringes are not economically feasible because incorporation of a needle retraction mechanism (NRM) in the hypodermic syringes enhances overall cost of the hypodermic syringes to such a greater extent that they become beyond reach of general masses. Furthermore, the operation of safety features is not self-evident and therefore additional training is required to use the hypodermic syringes effectively. Also, the existing hypodermic syringes require exertion of additional force to activate the needle retraction mechanism after the injection process, which ultimately becomes optional to the operator. The forceful activation of the needle retraction mechanism also leads to back stroke and becomes painful for the patient as well as the healthcare practitioners. As a result of the back stroke, the needle shakes and damages tissues which may result in bleeding and abscess may also occur due to the tissue injury.
In addition, the existing hypodermic syringes include a needle which is retracted into a barrel under action of a spring after the injection process. However, in such kind of the hypodermic syringes, the needle is retracted too fast which may result in bursting out of blood under body pressure from punctured hole on the body, which further brings secondary cross infections. The conventional hypodermic syringes also lack full-proof locking arrangement as well as effective retraction mechanism to prevent and restrict further use of the hypodermic syringes once used. Also, these hypodermic syringes do not include a fluid collecting device for collecting a fluid.
In order to effectively address the existing problems and shortcomings, there remains a constant need in the art for an efficient fluid injecting system and a method thereof, for safely injecting a fluid without any risk of needle stick injury. Further, we need such a fluid injecting system capable of not merely retracting the hypodermic needle following its use, but also capable of capturing and firmly retaining the used hypodermic needle in the retracted position within the system rendering it non-reusable. The proposed fluid injecting system not only addresses all such known alarming issues effectively, but also provides a clean, green, cheap, user-friendly and reliable technological advancement over the known alternatives.